Methods of reducing or eliminating pathogenic bacteria

ABSTRACT

Disclosed are methods for killing or reducing the incidence of pathogenic bacteria, comprising contacting the bacteria with a PURAC CL 21/80 solution (1-2.5% by weight) comprising lactic acid in an amount ranging from about 0.43% to 1.23% by weight and citric acid in an amount ranging from about 0.29% to about 0.88% by weight. In some aspects, the pathogenic bacteria can be present on a meat product.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/118,576, filed Dec. 10, 2020, now U.S. Pat. No. 11,185,083, issuedNov. 30, 2021, which is a continuation of U.S. patent application Ser.No. 16/443,646, filed Jun. 17, 2019, which is a continuation-in-part ofU.S. patent application Ser. No. 15/941,880, filed Mar. 30, 2018, nowU.S. Pat. No. 10,834,933, which is a continuation of U.S. patentapplication Ser. No. 12/806,317, filed Mar. 30, 2018, which claimspriority to U.S. Provisional Application No. 61/274,282, filed Aug. 14,2009, and which is a continuation-in-part of U.S. patent applicationSer. No. 12/151,826, filed May 9, 2008, which claims priority to U.S.Provisional Application No. 61/070,453, filed Mar. 22, 2008, and U.S.Provisional Application No. 60/928,941, filed May 11, 2007. Each ofthese documents is incorporated by reference in its entirety.

BACKGROUND

Food safety is an important concern, particularly with respect to meatssuch as poultry and other non-poultry meats. Uncooked meat products aresusceptible to contamination with pathogenic bacteria. Two examples areSalmonella and E. coli. During processing, meats are conventionallytreated with antimicrobial chemicals such as sodium chlorite, peraceticacid, acidified calcium sulfate, chlorine bleach, or another processingaid approved by the U.S. Department of Agriculture (USDA). Conventionalprocessing methods, however, are often ineffective at reducing theincidence of pathogenic bacteria. Accordingly, a need in the art existsfor improved processing methods. These needs and others are met by thefollowing disclosure.

SUMMARY

In one aspect, disclosed is a method of killing pathogenic bacteriacomprising contacting the bacteria with a solution of PURAC CL 21/80.The solution of PURAC CL 21/80 can comprise lactic acid in an amountranging from about 0.43% to 1.23% by weight and citric acid in an amountranging from about 0.29% to about 0.88% by weight.

In a further aspect, disclosed is a method of reducing pathogenicbacteria contamination on meat comprising treating the meat with asolution of PURAC CL 21/80. The solution of PURAC CL 21/80 can compriselactic acid in an amount ranging from about 0.43% to 1.23% by weight andcitric acid in an amount ranging from about 0.29% to about 0.88% byweight.

In a still further aspect, disclosed is a method of killing Salmonellacomprising contacting the Salmonella with a solution of PURAC CL 21/80.The solution of PURAC CL 21/80 can comprise lactic acid in an amountranging from about 0.43% to 1.23% by weight and citric acid in an amountranging from about 0.29% to about 0.88% by weight.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawing, which is incorporated in and constitutes partof this specification and together with the description, serves toexplain the principles of the disclosure.

FIG. 1 is a process flow diagram illustrating an exemplary aspect ofprocessing meat, e.g., poultry, according to a disclosed method.

DETAILED DESCRIPTION

In one aspect, disclosed is a method of killing pathogenic bacteria. Themethod comprises contacting the bacteria with a solution of PURAC CL21/80. The solution of PURAC CL 21/80 can comprise lactic acid in anamount ranging from about 0.43% to 1.23% by weight and citric acid in anamount ranging from about 0.29% to about 0.88% by weight. The pathogenicbacteria can be Salmonella, E. coli, or a combination thereof. Accordingto one aspect, the pathogenic bacteria (e.g., Salmonella, E. coli, or acombination thereof) can be present on a meat, e.g., poultry.

In a further aspect, disclosed is a method of reducing pathogenicbacteria contamination on meat comprising treating the meat with asolution of PURAC CL 21/80, wherein the solution of PURAC CL 21/80comprises lactic acid in an amount ranging from about 0.43% to 1.23% byweight and citric acid in an amount ranging from about 0.29% to about0.88% by weight. The pathogenic bacteria can be Salmonella, E. coli, ora combination thereof.

In a still further aspect, disclosed is a method of killing Salmonellacomprising contacting the Salmonella with a solution of PURAC CL 21/80,wherein the solution of PURAC CL 21/80 comprises lactic acid in anamount ranging from about 0.43% to 1.23% by weight and citric acid in anamount ranging from about 0.29% to about 0.88% by weight. In one aspect,the Salmonella can be present on a meat product.

PURAC CL 21/80 is a commercially-available product, sold by PuracAmerica, Inc., Lincolnshire, Ill., among others. PURAC CL 21/80comprises lactic acid in an amount ranging from about 43% to about 49%by weight and citric acid in an amount ranging from about 29% to about35% by weight. When applied to pathogenic bacteria (e.g., Salmonella orE. coli) or a meat product such as poultry or beef contaminated withpathogenic bacteria, PURAC CL 21/80 can be diluted to a solutioncomprising from about 1% to about 2.5% by weight of PURAC CL 21/80. Sucha solution of PURAC CL 21/80 is surprisingly and unexpectedly effectiveat killing or reducing the incidence of pathogenic bacteria, includingpathogenic bacteria present on meat such as poultry or beef.

Because PURAC CL 21/80 comprises lactic and citric acid in amountsranging from 43-49% and 29-35% by weight, respectively, the weightratios of lactic acid to citric acid in the PURAC 21/80 product canrange from about 1.2:1 (lactic acid:citric acid) to about 1.7:1 (lacticacid:citric acid). Thus, the diluted solutions of PURAC CL 21/80 (1-2.5%by weight) can also comprise a range of from about 1.2:1 (lacticacid:citric acid) to about 1.7:1 (lactic acid:citric acid), by weight.In one aspect, the diluted solutions of PURAC CL 21/80 (1-2.5% byweight) can comprise a range of from about 1.48:1 (lactic acid:citricacid) to about 1.4:1 (lactic acid:citric acid), by weight.

In a further aspect, the solution of PURAC 21/80 can be diluted to 1.8%to 2% by weight of PURAC 21/80. Thus, the 1.8% diluted solution cancomprise from about 0.77% lactic acid by weight to about 0.88% lacticacid by weight, and 0.52% citric acid by weight to about 0.63% citricacid by weight. Similarly, the 2% diluted solution can comprise fromabout 0.86% lactic acid by weight to about 0.98% lactic acid by weight,and 0.58% citric acid by weight to about 0.70% citric acid by weight.Such a solution can be applied to a meat product such as poultry orbeef, to reduce the incidence of pathogenic bacteria, includingSalmonella, E. coli, or a combination thereof.

The table below lists specific, non-limiting examples of PURAC CL 21/80and solutions of PURAC CL 21/80 diluted to 1% by weight, 1.5% by weight,2% by weight, and 2.5% by weight. The respective amounts of lactic acidand citric acid, as well as lactic acid:citric acid ratios are shown foreach example. The diluted solutions described in the table below can beused to reduce or kill pathogenic bacteria and can be applied to a meatproduct such as poultry or beef, to reduce the incidence of pathogenicbacteria on the meat, including Salmonella, E. coli, or a combinationthereof.

PURAC CL PURAC CL PURAC CL PURAC CL PURAC CL Lactic 21/80 21/80 (1%)21/80 (1.5%) 21/80 (2%) 21/80 (2.5%) Acid: Lactic Citric Lactic CitricLactic Citric Lactic Citric Lactic Citric Citric Acid Acid Acid AcidAcid Acid Acid Acid Acid Acid Acid 43% 29% 0.43% 0.29% 0.65% 0.44% 0.86%0.58% 1.08% 0.73% 1.48:1 43% 30% 0.43% 0.30% 0.65% 0.45% 0.86% 0.60%1.08% 0.75% 1.43:1 43% 31% 0.43% 0.31% 0.65% 0.47% 0.86% 0.62% 1.08%0.78% 1.39:1 43% 32% 0.43% 0.32% 0.65% 0.48% 0.86% 0.64% 1.08% 0.80%1.34:1 43% 33% 0.43% 0.33% 0.65% 0.50% 0.86% 0.66% 1.08% 0.83% 1.30:143% 34% 0.43% 0.34% 0.65% 0.51% 0.86% 0.68% 1.08% 0.85% 1.26:1 43% 35%0.43% 0.35% 0.65% 0.53% 0.86% 0.70% 1.08% 0.88% 1.23:1 44% 29% 0.44%0.29% 0.66% 0.44% 0.88% 0.58% 1.10% 0.73% 1.52:1 44% 30% 0.44% 0.30%0.66% 0.45% 0.88% 0.60% 1.10% 0.75% 1.47:1 44% 31% 0.44% 0.31% 0.66%0.47% 0.88% 0.62% 1.10% 0.78% 1.42:1 44% 32% 0.44% 0.32% 0.66% 0.48%0.88% 0.64% 1.10% 0.80% 1.38:1 44% 33% 0.44% 0.33% 0.66% 0.50% 0.88%0.66% 1.10% 0.83% 1.33:1 44% 34% 0.44% 0.34% 0.66% 0.51% 0.88% 0.68%1.10% 0.85% 1.29:1 44% 35% 0.44% 0.35% 0.66% 0.53% 0.88% 0.70% 1.10%0.88% 1.26:1 45% 29% 0.45% 0.29% 0.68% 0.44% 0.90% 0.58% 1.13% 0.73%1.55:1 45% 30% 0.45% 0.30% 0.68% 0.45% 0.90% 0.60% 1.13% 0.75% 1.50:145% 31% 0.45% 0.31% 0.68% 0.47% 0.90% 0.62% 1.13% 0.78% 1.45:1 45% 32%0.45% 0.32% 0.68% 0.48% 0.90% 0.64% 1.13% 0.80% 1.41:1 45% 33% 0.45%0.33% 0.68% 0.50% 0.90% 0.66% 1.13% 0.83% 1.36:1 45% 34% 0.45% 0.34%0.68% 0.51% 0.90% 0.68% 1.13% 0.85% 1.32:1 45% 35% 0.45% 0.35% 0.68%0.53% 0.90% 0.70% 1.13% 0.88% 1.29:1 46% 29% 0.46% 0.29% 0.69% 0.44%0.92% 0.58% 1.15% 0.73% 1.59:1 46% 30% 0.46% 0.30% 0.69% 0.45% 0.92%0.60% 1.15% 0.75% 1.53:1 46% 31% 0.46% 0.31% 0.69% 0.47% 0.92% 0.62%1.15% 0.78% 1.48:1 46% 32% 0.46% 0.32% 0.69% 0.48% 0.92% 0.64% 1.15%0.80% 1.44:1 46% 33% 0.46% 0.33% 0.69% 0.50% 0.92% 0.66% 1.15% 0.83%1.39:1 46% 34% 0.46% 0.34% 0.69% 0.51% 0.92% 0.68% 1.15% 0.85% 1.35:146% 35% 0.46% 0.35% 0.69% 0.53% 0.92% 0.70% 1.15% 0.88% 1.31:1 47% 29%0.47% 0.29% 0.71% 0.44% 0.94% 0.58% 1.18% 0.73% 1.62:1 47% 30% 0.47%0.30% 0.71% 0.45% 0.94% 0.60% 1.18% 0.75% 1.57:1 47% 31% 0.47% 0.31%0.71% 0.47% 0.94% 0.62% 1.18% 0.78% 1.52:1 47% 32% 0.47% 0.32% 0.71%0.48% 0.94% 0.64% 1.18% 0.80% 1.47:1 47% 33% 0.47% 0.33% 0.71% 0.50%0.94% 0.66% 1.18% 0.83% 1.42:1 47% 34% 0.47% 0.34% 0.71% 0.51% 0.94%0.68% 1.18% 0.85% 1.38:1 47% 35% 0.47% 0.35% 0.71% 0.53% 0.94% 0.70%1.18% 0.88% 1.34:1 48% 29% 0.48% 0.29% 0.72% 0.44% 0.96% 0.58% 1.20%0.73% 1.66:1 48% 30% 0.48% 0.30% 0.72% 0.45% 0.96% 0.60% 1.20% 0.75%1.60:1 48% 31% 0.48% 0.31% 0.72% 0.47% 0.96% 0.62% 1.20% 0.78% 1.55:148% 32% 0.48% 0.32% 0.72% 0.48% 0.96% 0.64% 1.20% 0.80% 1.50:1 48% 33%0.48% 0.33% 0.72% 0.50% 0.96% 0.66% 1.20% 0.83% 1.45:1 48% 34% 0.48%0.34% 0.72% 0.51% 0.96% 0.68% 1.20% 0.85% 1.41:1 48% 35% 0.48% 0.35%0.72% 0.53% 0.96% 0.70% 1.20% 0.88% 1.37:1 49% 29% 0.49% 0.29% 0.74%0.44% 0.98% 0.58% 1.23% 0.73% 1.69:1 49% 30% 0.49% 0.30% 0.74% 0.45%0.98% 0.60% 1.23% 0.75% 1.63:1 49% 31% 0.49% 0.31% 0.74% 0.47% 0.98%0.62% 1.23% 0.78% 1.58:1 49% 32% 0.49% 0.32% 0.74% 0.48% 0.98% 0.64%1.23% 0.80% 1.53:1 49% 33% 0.49% 0.33% 0.74% 0.50% 0.98% 0.66% 1.23%0.83% 1.48:1 49% 34% 0.49% 0.34% 0.74% 0.51% 0.98% 0.68% 1.23% 0.85%1.44:1 49% 35% 0.49% 0.35% 0.74% 0.53% 0.98% 0.70% 1.23% 0.88% 1.40:1

According to one aspect, the solution of PURAC CL 21/80 can be dilutedto 1% by weight of PURAC CL 21/80. Thus, the 1% by weight solution ofPURAC CL 21/80 can comprise from about 0.43% to about 0.49% by weightlactic acid and from about 0.29% to about 0.35% by weight citric acid.In a further aspect, the solution of PURAC CL 21/80 can be diluted to1.5% by weight of PURAC CL 21/80. Thus, the 1.5% by weight solution ofPURAC CL 21/80 can comprise from about 0.65% to about 0.74% by weightlactic acid and from about 0.44% to about 0.53% by weight citric acid.In a still further aspect, the solution of PURAC CL 21/80 can be dilutedto 2% by weight of PURAC CL 21/80. Thus, the 2% by weight solution ofPURAC CL 21/80 can comprise from about 0.86% to about 0.98% by weightlactic acid and from about 0.58% to about 0.7% by weight citric acid. Ina yet another aspect, the solution of PURAC CL 21/80 can be diluted to2.5% by weight of PURAC CL 21/80. Thus, the 2.5% by weight solution ofPURAC CL 21/80 can comprise from about 1.08% to about 1.23% by weightlactic acid and from about 0.73% to about 0.88% by weight citric acid.In a further aspect, the solution of PURAC CL 21/80 can be diluted to1-2.3% by weight PURAC CL 21/80.

In some aspects, the solution of PURAC CL 21/80 can consist essentiallyof lactic acid and citric acid in any of the disclosed amounts andratios. According to this aspect, other substances can be present in thesolution of PURAC CL 21/80 as long as those other substances do notmaterially affect the antimicrobial properties of the PURAC CL 21/80solution. Thus, in one aspect, for example, other substances can bepresent in PURAC CL 21/80 solutions consisting essentially of lacticacid and citric acid in any of the disclosed amounts provided thoseother substances do not reduce the antimicrobial properties (e.g.,ability to kill Salmonella, E. coli, or a combination thereof) of thesolution by more than 10%.

Depending on the pH of the solution of PURAC CL 21/80, some of thelactic or citric acid can be present as lactate or citrate. The amountsof lactic acid and citric acid described herein contemplate that some ofthe acid may be in lactate or citrate form. Thus, in some aspects,depending on pH, PURAC CL 21/80 can comprise lactic acid and/or lactatein an amount ranging from about 43% to about 49% by weight and citricacid and/or citrate in an amount ranging from about 29% to about 35% byweight. Accordingly, when a PURAC CL 21/80 product is diluted to 1-2.5%by weight, the solution of PURAC CL 21/80 can comprise lactic acidand/or lactate in an amount ranging from about 0.43% to 1.23% by weightand citric acid and/or citrate in an amount ranging from about 0.29% toabout 0.88% by weight.

In one aspect, the pH of the solution applied to the pathogenicbacteria, e.g., Salmonella, E. coli, or a combination thereof, or to ameat product contaminated with such pathogenic bacteria, can be basic.For example, PURAC CL 21/80 can be slightly buffered with potassiumhydroxide or another suitable base such that a pH ranging from about 2to about 2.2 is maintained in a 10% solution of PURAC CL 21/80 in water.

The PURAC CL 21/80 product can in some aspects comprise potassium in anamount ranging from about 1.2-1.5% by weight. The density of PURAC CL21/80 at 20° C. can range from about 1.28-1.30 g/mL. PURAC CL 21/80 cancontain other impurities, including for example, chlorides up to 20mg/kg, sulfates up to 10 mg/kg, iron up to 10 mg/kg, heavy metals up to5 mg/kg, and lead up to 0.5 mg/kg.

According to one aspect, PURAC CL 21/80 solutions comprising lactic andcitric acids in any of the disclosed amounts can be used to treat a meatsuch as poultry. FIG. 1 depicts an exemplary production process forharvesting and processing poultry for market in accordance with adisclosed method. Live chickens can be brought into the production plantin crates. The chickens can be removed from the crates and hung upsidedown. In that position, their throats can be severed, so that the bloodcan drain thoroughly. The carcasses can then be put in a scalding tankwhere they can be treated for about 5-7 minutes with water at about138-142° F. The scalding prepares the carcass for removal of thefeathers. The scalding tank can promote cross-contamination of poultryentering the tank by contact with water contaminated by bacteria frompreviously processed poultry. The poultry can then be sent to one ormore “pluckers,” available in various configurations, for removal of thefeathers. The de-feathered carcasses can be rinsed with potable water,also at about 138-142° F. The hot water rinse assists in final removalof any residual feathers.

The carcasses can then be placed on an automated evisceration andinspection line. Along the line the poultry are eviscerated, anyremaining heads are removed, and parts that appear visibly contaminatedcan be cut off. The carcasses can then be subjected to a final rinsewith water at ambient temperature. After the plucking step and the hotwater rinse, the de-feathered carcasses can subjected to anantimicrobial spray using a solution of PURAC CL 21/80 as describedherein. The spray can be applied for about 1 to 6 seconds to eachcarcass as the carcasses pass through a spray booth. This process step(i.e., antimicrobial spray following plucking) alone resulted in areduction of about 30% in the incidence of Salmonella on carcassestreated to this same point (i.e., hot water rinse after plucking)according to a conventional process. According to a further aspect, theantimicrobial PURAC CL 21/80 spray can be applied after plucking butbefore the hot water rinse.

Following the initial antimicrobial treatment with PURAC CL 21/80, thecarcasses can be placed on the evisceration line and processed.According to one aspect, it can be useful to again apply a solution ofPURAC CL 21/80 in the post-evisceration antimicrobial control. Onenon-limiting method of applying the PURAC CL 21/80 solution is to use a“dip.” The carcasses can be placed in the dip for about 10 seconds toapproximately one minute. The bath can be monitored to make sure thatthe concentration of PURAC CL 21/80 remains in a range of from about 1%to about 2.5% by weight. If the concentration exceeds 2.5%, in someaspects, the carcasses may develop an undesirable gray color andobjectionable odor. One way to help control the concentration of PURACCL 21/80 is to slowly feed, e.g., “drip,” antimicrobial solution intothe dip tank. Alternatively, the antimicrobial solution can be added tothe tank and blended with water to the desired concentration. Theconcentration can be monitored about every 15-20 minutes to ensure thatthe concentration is maintained at a suitable level. The use of theantimicrobial PURAC CL 21/80 dip results in a 90% reduction inSalmonella, i.e., 90% of the poultry carcasses with Salmonella beforetreatment can be Salmonella-free after treatment.

Following the antimicrobial PURAC CL 21/80 dip, a rinse can be carriedout using potable water or any other USDA approved final rinse step,such as chlorinated water, within the approved concentration(s). In thecase of a chlorinated water rinse, a typical concentration is betweenabout 20-50 ppm. Each carcass can be subjected to the spray for betweenabout 1 to 6 seconds. After the treatment with the aqueous chlorinespray, the carcasses can be sent into an air chiller. In the event thatthe production facility uses an ice bath for chilling, the chlorine (orother USDA approved substance at proper concentration(s)) can be addedto the ice bath rather than using a separate spray.

In a further aspect, the PURAC CL 21/80 solutions comprising lactic andcitric acid in any of the disclosed amounts can be used to treat beefand other non-poultry meats, e.g., pork, lamb, goat, rabbit, amongothers. The disclosed PURAC CL 21/80 solutions can be used on livestockcarcasses both pre-chill and post-chill and in addition can be used onoffal and variety meats. The PURAC CL 21/80 solutions (1-2.5%) can beused on beef and pork primals and trimmings at 55° C., according to oneaspect. In one aspect, the PURAC CL 21/80 solutions can be applied at2-2.5 wt. % to the brushes in the spray cabinets used on beef heads andtongues.

The disclosed PURAC CL 21/80 solutions can be applied at differentplaces in the meat packing plant. One point of application isimmediately after carcass wash. Another point of application is in thehot box. Some meat packing plants currently employ multiple contaminanthurdles (e.g., application of antimicrobial products, washing, and thelike) at various points in the meat processing, and the application ofPURAC CL 21/80 can be used as part of one of those steps. In otherwords, the disclosed solutions of PURAC CL 21/80 can be the principalantimicrobial treatment or can be used with other processing steps.

When the PURAC CL 21/80 solutions are used in the post-processing ofmeat, one non-limiting method of application is to spray the meat beforecutting or needling. In commercial applications, this can occur at aspray station as the meat passes on a conveyor. It can also be desirableto again apply the antimicrobial PURAC CL 21/80 solution after thecutting or needling operation or to apply it on the cutting blade(s) orneedles (s) prior to their contacting the meat.

EXAMPLES

The following examples are put forth so as to provide those of ordinaryskill in the art with a complete disclosure and description of how themethods claimed carried out and evaluated, and are intended to be purelyexemplary and are not intended to limit the scope of what the inventorsregard as their invention. Efforts have been made to ensure accuracywith respect to numbers (e.g., amounts, temperature, etc.), but someerrors and deviations should be accounted for. Unless indicatedotherwise, parts are parts by weight, temperature is in ° C. or is atambient temperature, and pressure is at or near atmospheric. TheExamples are provided herein to illustrate the disclosure, and shouldnot be construed as limiting in any way.

1. Example 1

A test was performed on commercially processed chicken carcasses todetermine the antimicrobial efficacy of a post-evisceration dipemploying a solution of citric acid and lactic acid (PURAC CL21/80) in apost-evisceration, dip tank. The production line from which the samplecarcasses were obtained utilized a process as shown in FIG. 1.

Seventy-five chicken carcasses were removed from the production linepost evisceration. Twenty-five poultry were evaluated at this stage by aUSDA certified laboratory for aerobic plate counts (“APC”), genericE-coli, and the presence or absence of Salmonella spp. Of thetwenty-five carcasses, ten were evaluated for APC and E-Coli and alltwenty-five for Salmonella spp.

The remaining fifty carcasses were then processed in a dip tankcontaining a solution of PURAC CL 21/80. The solution was monitored andmaintained within a target concentration of 1.80% to 2.00%. The actualconcentrations in the dip tank varied from 1.80% to 2.04% throughout thestudy period. The concentration was monitored by periodic taking asample of a known size from the solution and titrating the sample onsite. The chicken carcasses were treated in the dip for approximately 60seconds. Ten chicken carcasses were then evaluated for APC and E-coli(10 carcasses), and all 25 carcasses were evaluated for the presence ofSalmonella spp. The remaining twenty-five chicken carcasses were sent tothe chiller and then examined for Salmonella spp.

The chicken carcasses were rinsed in accordance with the MicrobiologyLaboratory Guidebook, Chapter 4.03, Section 4.5.7 Whole Bird Rinses,published by the United States Department of Agriculture (“USDA”). Thecarcasses were rinsed with 400 mL of Butterfield's Phosphate Diluent asdescribed in the note; this was done in order to also evaluate APC andgeneric E. coli values from the rinse solution for each bird.

Upon arrival at the laboratory the chicken rinses were processed for theevaluation of APC, generic E. coli and Salmonella spp. APC were preparedand evaluated in accordance with the Food and Drug Administration'sBacteriological Analytical Manual (“FDA-BAM”), 8th Edition, Revision A,1998. Generic E. coli were prepared and evaluated in accordance withAOAC Official Method of Analysis 991.14. AOAC Official Method ofAnalysis 996.08 was performed to analyze the chicken rinses for thepresence or absence of Salmonella spp.

The data and cumulative results for APC and E-coli pre-dip and post-dipare shown in Table 1. The data for Salmonella spp. pre-dip, post-dip andpost chiller are shown in Table 2. (The data for APC and E. coli in agiven row in the table represents the test data for a single sample birdpre-dip and a single sample bird post-dip.)

TABLE 1 APC APC E. coil E. coli (pre-dip) (post-dip) (Pre-dip)(post-dip) Log order Log order Log order Log order CFU/mL CFU/mL CFU/mLCFU/mL 5.56 2.94 2.81 0.00 5.68 2.99 3.04 1.04 5.79 3.08 2.40 0.00 5.402.81 3.15 0.95 5.49 2.72 3.11 0.78 5.54 2.89 2.84 0.00 5.46 2.77 2.920.30 5.83 3.00 2.75 0.00 5.62 2.83 3.00 0.60 5.43 2.81 2.57 0.00 AverageLog 10 5.58 2.88 2.86 0.37

The lactic acid blend demonstrated a 2.32 to 3.12 log 10 reduction inaerobic plate counts and generic E. coli counts showed a 1.36 to 3.15log 10 reduction (See Table 1.) Five of 10 the chicken rinses hadgeneric E. coli counts of less than 10 colony forming units/ml (CFU/ml);these are represented by the 0.00 in the E. coli (post-lactic) column ofTable 1. These figures represent the bacterial loads after the IOBW andprior to the chilling of the chicken carcasses.

TABLE 2 # Positive % Positive #Negative % Negative Pre-dip 23 92 2 8Post-dip 1 4 24 96 Post-Chill 1 4 24 96

Of the twenty-five carcasses rinsed at the pre-antimicrobial blendinterval (after IOBW, prior to dip tank) twenty-three of the chickenrinses tested positive for Salmonella spp. After exposure to theantimicrobial blend in the dip tank, (post-lactic, pre-chill) only oneof the chicken rinses tested positive, with the remaining twenty-fourcarcasses being negative for Salmonella spp. At the post-chill intervaltwenty-four out of the twenty-five tested negative, with only one beingpositive (See Table 2). Although no further confirmation testing wasperformed, the screen procedure used in this study has a highsensitivity for meat products with 99% specificity. Certain strains ofCitrobacter or Hafnia have showed some cross-reactivity with thescreening method utilized. The results from this study indicate that theuse of a citric acid/lactic acid blend in a dip tank system is effectivein the reduction of pathogenic bacteria including Salmonella.

2. Example 2

Tests were performed to determine the efficacy of using a mixture ofcitric acid and lactic acid in solution on commercially processedchickens at various points in the poultry harvesting process. Thesolution contained approximately 2.5% of PURAC CL21/80.

Sample chicken carcasses were obtained from a production line utilizinga process as shown in FIG. 1. Sample carcasses were removed from theproduction process and were treated with the antimicrobial solution asshown in Table 3 and the following description. Spray times were what ittook to completely cover the bird with solution and dip times were whatit took to manually dunk the bird in a bucket and pull it out. In eachcase contact time was about 1 to 6 seconds.

Sample 16 (pre-evisceration) was placed in a 5 gallon bucket containinga 2.5% solution of PURAC CL21/80. The sample was dipped down and thenbrought back to the surface for a residence time of about 1 to 6 secondsin the solution. Sample 18 was sprayed with a solution of CL21/80 usinga pump sprayer as the carcass was rotated and covered well with thesolution. The dip was the same as for sample 16. Sample 20 was a controlsample taken after the plucker. Sample 21 was a control sample takenjust before entering the chiller. It had been sprayed using acombination of citric acid and sodium chlorite sold under the trademarkSANOVA by Alcide Corporation, Redmond, Wash. and now a part of Ecolab,Inc., St. Paul, Minn.). Sample 22 (post-evisceration) was taken from adifferent place on the line, but treated the same as sample 18. Sample23 was sprayed with Purac CL21/80 pre-evisceration and dipped in a 20ppm chlorine dioxide solution post-evisceration.

TABLE 3 (Sample Treatment with Results Carcass 2.5% CL 21/80 AnalysisMethod CFU/gram 16 Single dip— Aerobic Plate FDA 42,000 pre-eviscerationCount BAM 16 — Coliform AOAC 90 18 Pre-evisceration Aerobic Plate FDA<10 spray and Count BAM post-evisceration dip 18 Coliform AOAC <10 20Control— Aerobic Plate FDA 260,000 no treatment Count 20 — Coliform AOAC1,200 21 — Aerobic Plate FDA 130,000 Count BAM 21 — Coliform AOAC 1,20022 Post-evisceration Aerobic FDA 49,000 spray Plate Count BAM 23Pre-evisceration Aerobic Plate FDA 170,000 spray and post Count BAMevisceration chlorine dioxide dip 23 — Coliform AOAC 780

3. Example 3

A test was performed to determine the efficacy of using a 2.5% solutionof citric acid and lactic acid (PURAC CL21/80) as a spray oncommercially processed chicken carcasses pre-evisceration. Samplecarcasses were removed from the production process and sprayed forapproximately 1 to 6 seconds with the antimicrobial solution. Theresults are shown in Table 4. The APC was determined utilizing the FDABAM method. All other tests results were obtained using AOAC.

TABLE 4 (Sample Aerobic Plate Count Coliform Mold Count Yeast CountCarcass) (CFU/mL) (CFU/mL) (CFU/mL) (CFU/mL) 1 900 80 <10 20 (CL21/80 A)2 1800 60 <10 <10 (CL21/80 B) 3 23,000 620 20 <10 (Control A) 4 146,000810 30 10 (Control B)

4. Example 4

A study was performed by an independent laboratory to verify theeffectiveness of using a solution of citric acid and lactic acid (PURACCL21/80) to reduce Escherichia coli 0157:H7 and Salmonella in beef. Inparticular, the study used USDA Select, beef tips (Beef Bottom SirloinButt, Tri-Tip, Boneless IMPS 185C) which were obtained directly from acommercial processing facility, i.e., a meat packing plant, and thentransported to a pathogen processing facility.

Upon arrival, loins were fabricated for uniformity and inoculated witheither a cocktail mixture of E. coli 0157:H7 or Salmonella (two separateinoculations) by dipping the sub-primals in a pathogen inoculated buffersolution at a 104 cfu/ml (high). A total of 5 tips/treatment/pathogenwere prepared for a total of 30 tips as follows: Five samples ofnon-inoculated control (NC); Five samples of non-inoculated withtreatment spray (NT); Five samples of Escherichia coli 0157:H7 control(EC); Five samples of Escherichia coli 0157:H7 treated (BT); Fivesamples of Salmonella control (SC); Five samples of Salmonella treated(ST).

Inoculated tips were placed on stainless steel racks and held atrefrigerated temperatures (approximately 4° C.) for one hour tofacilitate “attachment.” After the attachment period, one-half of theinoculated samples were treated with the solution of citric and lacticacids. The solution was placed into a trim sanitizing spray cabinet. Thebeef tips were moved along by chain at the rate of one foot per 2.5seconds. Equipment was cleaned and sanitized between each sample andtreatment combination. The antimicrobial solution was employed at aconcentration of 2.5 wt. %. and at a temperature of approximately 77° F.The solution was applied at a rate of about 0.66 gallons per minute forabout 1.5 to 1.75 seconds. The spray cabinet had six nozzles of size1101.5 each.

The controls and treated samples were then subjected to microbiologicalanalysis. The external surface of each of the tips was swabbed (100 cm²area) to determine pathogen loads on the surface of the product. Theswab was placed into a sterile whirl pack bag with 10 mL of peptonebuffer. Appropriate dilutions and plating followed. The non-inoculatedcontrol and non-inoculated treatment were serially diluted and platedonto MAC and APC agar. The samples containing E. coli 0157:H7 wereserially diluted using peptone dilution blanks and plated onto MSA witha thin-layer of TSA for cell recovery to detect total numbers remainingon the product. Samples containing Salmonella were serially diluted andplated onto XLD agar with a thin-layer of TSA for cell recovery todetermine the survival of the Salmonella.

The data was then analyzed statistically using a descriptive analysis inSAS program. If a plate revealed no colonies, a count of one cfu/100 cm²was recorded in the data set for statistical program analysis purposes.The study revealed the following results: The beef tips had an initialaerobic plate count of log 3.5 cfu/100 cm² and a generic Escherichiacoli count of log 1.5 cfu/100 cm². After the beef tips were dipped intothe solution of citric and lactic acids, the aerobic plate countsdecreased by 1.5 logs while the generic Escherichia coli decreased by0.4 logs. For pathogen recovery, the beef tips were inoculated to log5.5 c in/100 cm² with Escherichia coli 0157:H7 and Salmonella. Aftertreatment, the Escherichia coli 0157:H7 was reduced by 1.4 logs and theSalmonella species by 1.1 logs.

5. Example 5

The use of a solution of citric and lactic acids (PURAC CL21/80) toreduce the incidence of E-coli and Salmonella was also verified in aexperimental test at a commercial slaughtering facility that normallyused a solution of 5 wt. % lactic acid applied to full carcasses on thekill floor. As an alternative to the lactic acid treatment, the plantused a 2.5 wt. % solution of citric and lactic acids also applied on thekill floor during its normal production for a period of several days.Routine quality control tests were performed to detect the presence ofboth Salmonella and E-coli on the treated meat. The results were atleast as good as those normally achieved with lactic acid alone athigher concentration levels.

Other examples are described in U.S. Provisional Application No.61/274,282, filed Aug. 14, 2009, U.S. Non-Provisional application Ser.No. 12/806,317, filed Aug. 10, 2020, U.S. Non-Provisional applicationSer. No. 15/941,880, filed Mar. 20, 2018 (now U.S. Pat. No. 10,834,933),and U.S. Non-Provisional application Ser. No. 16/443,646 (filed Jun. 17,2019). Each of these documents is incorporated by reference in itsentirety, including each document's teachings of examples.

It will be apparent to those skilled in the art that variousmodifications and variations can be made without departing from thescope or spirit of this disclosure. Other embodiments will be apparentto those skilled in the art from consideration of the specification andpractice disclosed herein. It is intended that the specification andexamples be considered as exemplary only, with a true scope and spiritbeing indicated by the following claims.

What is claimed is:
 1. A method of killing pathogenic bacteria, themethod comprising contacting the pathogenic bacteria with a solutioncomprising lactic acid in an amount ranging from about 0.43% to 1.23% byweight and citric acid in an amount ranging from about 0.29% to about0.88% by weight.
 2. The method of claim 1, wherein the pathogenicbacteria is Salmonella, Escherichia coli, or a combination thereof. 3.The method of claim 1, wherein the pathogenic bacteria is present on ameat.
 4. The method of claim 3, wherein the meat is poultry.
 5. Themethod of claim 1, the solution consisting essentially of the lacticacid and the citric acid.
 6. A method of reducing pathogenic bacteriacontamination on meat, the method comprising treating the meat with asolution of PURAC CL 21/80, wherein the solution comprising lactic acidin an amount ranging from about 0.43% to 1.23% by weight and citric acidin an amount ranging from about 0.29% to about 0.88% by weight.
 7. Themethod of claim 6, wherein the pathogenic bacteria is Salmonella,Escherichia coli, or a combination thereof.
 8. The method of claim 6,the solution consisting essentially of the lactic acid and the citricacid.
 9. A method of killing Salmonella, the method comprisingcontacting the Salmonella with a solution comprising lactic acid in anamount ranging from about 0.43% to 1.23% by weight and citric acid in anamount ranging from about 0.29% to about 0.88% by weight.
 10. The methodof claim 9, wherein the Salmonella is present on a meat product.
 11. Themethod of claim 9, the solution consisting essentially of the lacticacid and the citric acid.